MarshaMallow84 how do you feel he is coping with the books he is bringing home?
Is he spending a fair bit of time decoding words or is he coping with 95%/97% of them without much effort?
Is he adding tone, expression and showing good understanding of what is going on in the story? (my DCs school does expect this at Gold level).
Does he understand what the longer words mean in the context that they are given in the books? (I often ask my DCs about the meaning of random/obscure words).
Does he read across a wide variety of books e.g. fiction, non-fiction, fact, poems?
Is your DC taking a long time to work through the books or is he getting through two or three a week?
Out of interest does the school not ask you to sign a reading record in which you can also leave notes if particular issues arise?
One thing is for certain, if your DC is not forming a solid foundation to his reading skills, it is going to get pretty tough when they move onto the lengthy chapter books.
To be fair to the teacher, given the high level of interest other children are showing towards moving through the book bands, she has likely had a fair few discussions from other parents demanding to know why their DC is not yet a free reader.